Feature: Vision

Leading Causes of Blindness

Cataracts

Cataracts are a clouding of the lenses in your eyes. They affect vision and are very common in older people. More than 22 million Americans have cataracts. They are the leading cause of blindness in the world. By age 80, more than half of all people in the United States either will have a cataract or have had cataract surgery.

Common symptoms are:

Blurry vision

Colors that seem faded

Glare

Not being able to see well at night

Double vision

Frequent prescription changes in your eye wear

Treatment with new glasses, brighter lighting, anti-glare sunglasses, or magnifying lenses can help at first. Surgery is also an option. It involves removing the cloudy lens and replacing it with an artificial lens. Wearing sunglasses and a hat with a brim to block ultraviolet sunlight may help to delay cataracts.

Glaucoma.
Photo courtesy of National Eye Institute, NIH

Glaucoma

Glaucoma damages the eye's optic nerve and is a leading cause of blindness. It usually happens when the fluid pressure inside the eyes slowly rises, damaging the optic nerve. Often there are no symptoms at first, but a comprehensive eye exam can detect it. About 2.3 million Americans suffer from glaucoma. It is estimated that an additional 2 million have the disease but don't know it.

Glaucoma is a leading cause of blindness among African Americans and Hispanics. African Americans experience glaucoma at a rate three times that of whites. They suffer blindness four times more frequently. Between the ages of 45 and 64, glaucoma is 15 times more likely to cause blindness in African Americans than in whites.

People at risk should get eye exams at least every two years, especially:

African Americans over age 40

People over age 60, especially Hispanics

People with a family history of glaucoma

Treatment usually includes prescription eye drops and/or surgery. There is no "cure" for glaucoma. Early diagnosis and treatment can control glaucoma before vision loss or blindness occurs. New research is focusing not only on lowering pressure inside the eye, but also exploring medications to protect and preserve the optic nerve from the damage that causes vision loss. There has been progress in understanding the genetics of glaucoma in the last few years, including the discovery of genes found to be associated with many forms of glaucoma.

Macular degeneration

Macular degeneration, often called age-related macular degeneration (AMD), is a leading cause of vision loss in Americans 60 and older. It is a disease that destroys the sharp, central vision needed to see objects clearly. This affects the ability to read, drive, watch television, and do routine daily tasks.

AMD affects the macula, the part of the eye that allows you to see fine detail. It does not hurt, but causes cells in the macula to die. In some cases, AMD advances so slowly that people notice little change in vision. In others, the disease progresses faster and may lead to vision loss in both eyes. There are two kinds of AMD—wet and dry. Wet AMD occurs when abnormal blood vessels behind the retina start to grow under the macula. Dry AMD occurs when the light-sensitive cells in the macula slowly break down, gradually blurring central vision in the affected eye.

Treatment: Although there is no cure for AMD at this time, regular eye exams can detect the disease so treatment can be most effective. Findings from the NEI-supported Age-Related Eye Disease Study (AREDS) show that a specific combination of vitamins and minerals can help slow the progression of advanced AMD. Treatments for wet AMD include laser surgery, photodynamic therapy, and drugs injected into the eye. The NEI recently started a clinical trial to compare the relative safety and effectiveness of two drugs currently used to treat wet AMD. The two drugs, which are injected into the eye, are Lucentis (ranibizumab) and Avastin (bevacizumab). NEI is also supporting AREDS2 to learn whether a modified combination of vitamins and minerals can further help people with AMD.

Diabetic Retinopathy

Diabetic retinopathy is caused by diabetes. It affects the retina, the light-sensitive tissue at the back of the eye, and causes the most blindness in U.S. adults. It affects the vision of more than half of the 18 million people diagnosed with diabetes age 18 or older.

People with diabetes should have a complete eye exam through dilated pupils at least once a year.

Treatment: Diabetic retinopathy is treated with surgery or laser surgery. With timely treatment; adequate control of blood sugar, blood pressure, and cholesterol levels; and regular follow up, 90 percent of all cases of blindness from diabetes can be prevented.